For example, Patent Literature 1 discloses a CC driving method which has been employed in an active matrix liquid crystal display device. The following description discusses CC driving with reference to what is disclosed in Patent Literature 1.
FIG. 52 illustrates an arrangement of a device which implements CC driving. FIG. 53 illustrates waveforms of respective signals, the waveforms being obtained during the CC driving implemented by the device of FIG. 52.
A liquid crystal display device which carries out CC driving includes an image display section 110, a source line driving circuit 111, gate line driving circuits 112, and CS bus line driving circuits 113 (see FIG. 52).
The image display section 110 includes a plurality of source lines (signal lines) 101, a plurality of gate lines (scanning lines) 102, switching elements 103, pixel electrodes 104, a plurality of CS (Capacity Storage) bus lines (common electrode lines) 105, retention capacitors 106, liquid crystals 107, and a counter electrode 109. The switching elements 103 are provided in the vicinity of intersections of the plurality of source lines 101 and the plurality of gate lines 102. The pixel electrodes 104 are connected to the respective switching elements 103.
Each of the CS bus lines 105 is paired with and is parallel to a corresponding gate line 102. Each of the retention capacitors 106 has one end which is connected to a corresponding pixel electrode 104 and the other end which is connected to a corresponding CS bus line 105. The counter electrode 109 is provided so as to face the pixel electrodes 104 via the liquid crystals 107.
The source line driving circuit 111 is provided so as to drive the plurality of source lines 101, and the gate line driving circuits 112 are provided so as to drive the plurality of gate lines 102. The CS bus line driving circuits 113 are provided so as to drive the plurality of CS bus lines 105.
Each of the switching elements 1.03 is made of amorphous silicon (a-Si), polycrystalline polysilicon (p-Si), single crystal silicon (c-Si), or the like. Such a structure forms a capacitor 108 between a gate and a drain of a switching element 3. The capacitor 108 causes a phenomenon such that a gate pulse from the gate line 102 shifts an electric potential of the pixel electrode 104 to a negative electric potential.
The liquid crystal display device is arranged such that a gate line 102 has an electric potential Vg that (i) is Von only during an H period (a horizontal scanning period) in which the gate line 102 is selected and (ii) is maintained at Voff during the other periods (see FIG. 53). Though an electric potential Vs of a source line 101 varies in its amplitude depending on a video signal to be displayed, a polarity of the electric potential Vs is reversed at a boundary of a counter electrode electric potential Vcom between Von and Voff every H period, and during an adjacent H period for the gate line 102, the electric potential Vs has a waveform such that the electric potential Vs has a reversed polarity (line reversal driving). Note that since FIG. 53 assumes that a uniform video signal is inputted, the electric potential Vs changes at a constant amplitude.
Since the switching element 103 turns on during the period in which the electric potential Vg is Von, an electric potential Vd of the pixel electrode 104 is identical to the electric potential Vs of the source line 101. At the moment the electric potential Vg becomes Voff, the electric potential Vd is slightly shifted toward a negative electric potential via the capacitor 108 formed between the gate and the drain of the switching element 3.
The CS bus line 105 has an electric potential Vc of Ve+ during a first H period and a second H period in each of which a corresponding gate line 102 is selected, the second H period following the first H period. The electric potential Vc changes to Ve− during a third H period following the second H period and is then maintained at Ve− until the next field. The change causes the electric potential Vd to be shifted toward a negative electric potential via the retention capacitor 106.
This causes the electric potential Vd to change at a higher amplitude than the electric potential Vs. Therefore, the electric potential Vs can change at a lower amplitude. This allows simplification of a circuit configuration and reduction in power consumption in the source line driving circuit 111.